The disclosed subject matter relates generally to subsea hydrocarbon production and, more particularly, to a subsea Christmas tree with condition monitoring.
In order to control a subsea well, a connection is established between the well and a monitoring and control station. The monitoring and control station may be located on a platform or floating vessel near the subsea installation, or alternatively in a more remote land station. The connection between the control station and the subsea installation is usually established by installing an umbilical between the two points. The umbilical may include hydraulic lines for supplying hydraulic fluid to various hydraulic actuators located on or near the well. The umbilical may also include electrical and or fiber optic lines for supplying electric power and also for communicating control signals and/or well data between the control station and the various monitoring and control devices located on or near the well.
Hydrocarbon production from the subsea well is controlled by a number of valves that are assembled into a unitary structure generally referred to as a Christmas tree. Christmas tree and wellhead systems have the principle functions of providing an interface to the in-well environment, allowing flow regulation and measurement, and permitting intervention on the well or downhole systems during the operational life of the well. The actuation of the valves in the Christmas tree is normally provided using hydraulic fluid to power hydraulic actuators that operate the valves. Hydraulic fluid is normally supplied through an umbilical running from a remote station located on a vessel or platform at the surface. Alternative systems using electrically based actuators are also possible.
In addition to the flow control valves and actuators, a number of sensors and detectors are commonly employed in subsea systems to monitor the state of the system and the flow of hydrocarbons from the well. Often a number of sensors, detectors and/or actuators are also located downhole. All these devices are controlled and/or monitored by a dedicated control system, which is usually housed in the remote control module. Control signals and well data are also exchanged through the umbilical.
Conventional Christmas trees typically only have a few sensors designed to provide information on the production process. These sensors fail to provide any information regarding the operation or efficiency of the Christmas tree or wellhead. If a particular sensor fails to operate accurately, it may provide errant information regarding the production process. Uncertainties in the accuracy of the well monitoring and the limited amount of data make it difficult to optimize the production process or to predict impending failures.
This section of this document is intended to introduce various aspects of art that may be related to various aspects of the disclosed subject matter described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the disclosed subject matter. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art. The disclosed subject matter is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.